In general, a circular knitting machine is composed of three sections which are a yarn supply section, a knitting section, and a cloth rolling section. The cylinder of the knitting section rotates about the center of the circular knitting machine, and a knitting needle is installed in a groove of the cylinder base and guided by a track of a cam to -displace up and down while the cylinder base is rotating. When the knitting needle displaces up and down in the groove of the cylinder base, the sinker is pushed out timely to carry out the knitting with the knitting needle. It is worth to note that the knitting needle will constantly rub with the groove of the cylinder base to produce a high heat of up to 90 degrees Centigrade during the knitting process. The high heat will affect the movement among components due to the thermal expansion, and also may cause a breaking of yarns and produce defective products since the yarns cannot bear the high heat.
In view of the foregoing shortcomings of the prior art, manufacturers design a heat dissipating device on the circular knitting machine (particularly at the cylinder base) to eliminate the high heat so produced. U.S. Pat. No. 5,737,942 entitled “Means for deterring lint and debris accumulation on the knitting element of a circular knitting machine” comprises a curved plate disposed between a horizontal frame plate and a circular frame plate to define an air chamber, an air pump for sending compressed air to the air chamber through an air supply hose, and the compressed air flows to the cylinder base and other peripheral components so as to achieve the effects of removing dusts and dissipating heat. U.S. Pat. No. 6,199,408 entitled “Cooling apparatus for knitting components” comprises a cover disposed between an intermediate ring and a lower ring to form a cylindrical chamber between a needle-selecting actuator and the cover, and a ventilation fan installed on the cover for guiding external air into the chamber and passing the air through an opening of the chamber for cooling the heat produced by the cylinder base and its peripheral components.
However, the foregoing heat dissipating device use the air at room temperature for dissipating the heat, and thus it can only reduce the high temperature produced by the friction between the knitting needle and the groove of the cylinder base to 80 degrees Centigrade, and the heat dissipating effect is very limited. Therefore, current manufacturers spare no efforts to overcome the shortcoming of the prior art whose heat dissipating effect is poor.